4.1 GENERAL
4.1.1 Scope1 This Part includes the supply and installation of motor starters and associated equipment. 4.1.2 References
1 The following standards shall be followed
BS EN 60947-4 Contactors and motor Starters
BS EN 60947-1, IEC 947 Low Voltage switchgear and control gear
BS EN 60439, IEC 439 Specification for low-voltage switchgear and control gear
assembly
BS EN 60073 Coding of indicating devices and actuators by colour and
supplementary means
4.2 PRODUCTS
4.2.1 Starters1 Motor starters shall be rated to carry the full load current of its rated duty at its most severe
load conditions. All starters shall be capable of a minimum of 10 starts per hour at 100% full load torque unless otherwise specified.
2 Motor starters shall be rated to carry the full load current of its rated duty at its most severe load conditions. All starters shall be capable of at least 20 starts per hour at 100 % full load torque.
3 In accordance with the current QGEWC regulations, motors up to and including 11 kW shall be started direct on line. Motors above 11 kW shall incorporate assisted starting.
4 Motor starters shall be housed in a separate cubicle compartment of the relevant motor control centre and each starter cubicle shall contain the following components, or as otherwise indicated on the Project Drawings or Project Documentation.
(a) 1 no. triple pole ACB or MCCB or fuse switch, as indicated on the Project Documents,
externally operated and interlocked with the cubicle door. There shall be provision for padlocking in the OFF position.
(b) 1 no. starter, comprising one of the following types, as indicated on the Project Drawings:
(i) direct on line (ii) star/delta
(iii) close transition star/delta (iv) reduced voltage “soft start” (v) rotor resistance
(vi) auto - transformer
(c) 1 no. motor protection relay, as specified in Part 3
(d) 1 no. set of auxiliary relays and timers required to provide the necessary indication and control sequence
(e) 1 no. set of main motor terminals and auxiliary terminals for remote controls and indications.
(f) 1 no. set of terminals for remote lock-off stop push buttons (g) 1 no. control circuit transformer, where applicable
(h) 1 no. anti-condensation heater
(i) 1 no. set of power factor correction capacitors with separate fuses for all drives above
11 kW, to give a power factor of not less than 0.85.
5 The components of the starter shall be type tested and ASTA certified to achieve Type 2 co- ordination in accordance with IEC 947.
6 The following equipment shall be mounted on the door of the starter cubicle, or as otherwise indicated in the Project Drawings or Project Documentation.
(a) 1 no. ammeter, 96 X 96, with 240° scale fitted with suppressed scale to read motor
running and starting current, with an adjustable red pointer to indicate full load current. The scale range shall be such that normal full load current gives approximately 60% full scale deflection.
(b) 2 no. pilot lamps to indicate “SUPPLY ON” (Green) and “MOTOR RUNNING” (Red). (c) 1 no. pilot lamp to indicate “MOTOR FAILED” (Amber)
(d) pilot lamps (a separate lamp for each motor fault conditions) (e) 1 no. “Hand/OFF/AUTO” Selector switch
(f) 1 set “Start/Stop” push button
(g) 1 no. externally operated overload reset push button
(h) 1 no. motor and cubicle heater “OFF/AUTO” control switch, where applicable
(i) 1 no. electronic hour counter reading to 99999 hours with analogue display, memory
and battery backup with reset button
(j) lamp test push button (k) 1 duty label.
7 All starters shall contain a totally enclosed dust proof timer, or the operation will be controlled by a timer in the automatic section, which shall prevent pump(s) starting after a power failure until after a pre-set time has elapsed. The timer(s) or contacts shall be adjustable in the range 50 to 200 percent of the anticipated maximum delay which shall be taken as twice the total time required for all pumps to start and run steadily having been started consecutively. The timer(s) or contacts shall be set to give individual sequential start after a power failure with no drive starting until its predecessor has reached full steady running.
4.2.2 DOL Starters
1 DOL starters shall consist of a TP contactor for switching direct on line in accordance with BS EN 60947-4-1 and fitted with auxiliary contacts.
2 Contactors shall be selected for category AC-3 duty. 4.2.3 Star Delta Starters
1 Star-delta starters shall be provided with contactors as for DOL starters, arranged in such a manner to ensure the star contactor opens before the delta contactor closes.
2 The period of running in star and the transition time shall be controlled by adjustable solid state type timers.
3 For closed transition type star-delta starters, further requirements shall be wire wound or
pressed sheet resistor banks of sufficient thermal rating to allow three (3) consecutive starts of 30 seconds period followed by a 15 minutes rest and another 30 seconds starting period. They shall also be of sufficient thermal rating to allow 10 starts per hour in line with the pump and starter specification unless otherwise specified. Resistance values shall be chosen to give a high starting current with low transient current. A thermal cut out shall be provided for transient resistance banks. Starter cubicles incorporating resistor banks shall be well ventilated and vermin proof with ventilation louvres.
4.2.4 Auto Transformer Starting
1 For auto-transformer starting there shall be provided magnetically operated starting,
accelerating and running contactors operating under adjustable electronic timing devices. The auto-transformers shall limit the starting current to 4 times full load current (FLC) with 60%, 70% and 80% tappings. The auto-transformer starting system shall be capable of 10 starts per hour, each of 15 seconds operation time and a reset time of 2 hours at the end. The auto-transformer shall also be capable of starting the duty motor 10 times in an hour under actual operating conditions.
4.2.5 Slip Ring Rotor Resistance Starters
1 Where slip ring rotor resistance motor starters are employed the rotor resistance shall be of the metal grid type and shall limit the starting current to that specified for the size of drive.
2 For slip ring rotor resistance starting there shall be provided magnetically operated starting, accelerating and running contactors, operating under mechanical or electronic timing devices.
3 Rotor resistance shall be mounted in floor standing units, panel top units or integral panel units, complying with the following requirements:
(a) floor standing units:
(i) the rotor resistance may be mounted within floor standing cubicle constructed of 2 mm (minimum ) thick sheet steel of welded construction
(ii) the cubicles shall be provided with adequate ventilation louvers and access to the resistance units shall be by means of a lockable, hinged front door
(iii) the cubicle shall be arranged for cabling from below
(iv) both the exterior and interior of the cubicle shall be stove enamelled to BS 4800 shade 14 E 53 and the exterior shall be provided with warning notices to indicate electrical hazard within
(v) each cubicle shall be equipped with a heater which shall be continuously “on” while the associated resistance bank is de-energised
(b) Panel Top Units:
(i) the rotor resistance may be mounted within separate cubicles mounted on top of the control panel. These cubicles shall be identical in construction to the control panel and dummy cubicles shall be provided as necessary to ensure uniform height of the entire control panel
(ii) the cubicles shall be provided with adequate ventilation louvers and access to the resistance units shall be by means of a lockable, hinged front door
(iii) cable connections to the main control panel shall be via suitable cable glands to maintain the integrity of the control panel enclosure
(iv) each cubicle shall be equipped with a heater which shall be continuously “on” while the associated resistance bank is de-energised.
(c) Integral Panel Units:
(i) the rotor resistance may be mounted within a cubicle with the control panel itself provided that:
• the resistance cubicle is adequately ventilated font and rear
• the resistance cubicle is provided with suitable cable gland entries to maintain the integrity of the control panel enclosure
• the resistance cubicle is located so that no electrical components are mounted above it
• the motor starter equipment is located in a separate, totally enclosed cubicle within the control panel
1 no. TP wound magnetic overload relay fully adjustable but set at the actual current setting required to trip under a stalled motor condition with the maximum time that the motor characteristic permits this condition to exist.
4.2.6 Reduced Voltage “Soft Starters”
1 Solid-state reduced voltage motor starters shall be closed transition, shunt duty type with
isolation contactor and bypass contactor. When the motor reaches full speed, the bypass contactor bypasses the soft starter power section. The solid-state power section shall consist of six silicon controlled rectifiers (two per phase connected back to back, in reverse parallel configuration) to provide soft start. The starters shall conform to the latest IEC Standards.
2 The starters shall use the current limit method of starting with the current adjustable between 150 percent and 425 percent of full load current of the motor. At turn-on, the control ramps up to the current limit in approximately 1 second and maintains that current until the motor comes up to full speed. If a problem exists and the motor fails to reach rated speed within a predetermined period of time, the control will shutdown. The starter shall provide a smooth, stepless acceleration and deceleration of the load from start to full speed and from full speed to stop. The starter shall be equipped with metal oxide varistor type surge suppressers across the SCR to protect against voltage transients and resistor/capacitor scrubber networks to protect against false firing of the SCR. Each SCR heat sink shall have a temperature sensor that shall shut the starter down in the event of an over temperature condition. When a starter failure occurs, the actual problem shall be indicated by an LED on the control panel front.
3 There shall be a overcurrent protective device, which shall provide over current protection and main disconnect function for the control unit. The position of the operating handle shall indicate “ON” or “OFF” position of the protective device and include provision for padlocking in the “OFF” position. This protective device shall be equipped with a shunt trip and shall trip when there is a SCR or plant power failure. Motor space heaters shall be energised when the motor is not running.
4 The reduced voltage starters shall be equipped with micro-processor controlled motor protection relays to control, monitor and protect the motors. The relay shall monitor three phase current and voltage and make trip and alarm decisions based on pre-programmed motor current and voltage conditions. Control functions shall include start detection, starter transition, incomplete sequence and number of starts per hour. The relay shall monitor and display load current of each phase, percent of full load current of each phase and running time. The relay shall protect the motor against time overcurrent, instantaneous overcurrent, underload, phase unbalance, earth fault, phase loss and phase reversal.
5 The manufacturer shall supply certified test results to confirm that the controller has been tested to substantiate designs according to applicable standards. The tests shall verify not only the performance of the unit and integrated assembly, but also the suitability of the enclosure venting, rigidity and bus bracing. In addition, the unit shall be factory tested in accordance with applicable standards.
6 Manufacturer shall be prepared to show proper evidence of having tested for noise immunity on both input and output power connections.
7 The softstarter shall be supplied factory configured ready to commission, without requiring
any parametering or reconfiguration at site.
8 The softstarter shall have the following protective feature as minimum:-
(a) over temperature
(b) overload (c) jam (d) stall
(e) phase Loss
(f) phase reversal
(g) shorted SCR
9 The softstarter shall have the following control feature as minimum:-
(b) ramp start 0-85% locked rotor torque – 1 to 60 seconds (c) current limit start 0-85% locked rotor current – 1 to 60 S
(d) soft stop 0 to 60 seconds
10 The softstarter shall be provided with high speed fuses as recommended.
4.3 INSTALLATION
1 The Contractor shall submit details of proposed equipment and method of installation to the Engineer and QGEWC for approval prior to commencement of installation work.
2 Provide all the motor control equipment installations, wiring installations and tests, including connections and interconnections for the electrical controls as indicated, specified and required. Assure proper fits for all equipment and materials in the spaces shown on the Drawings. The starter can be installed in a separate cubicle for MCC or can be an item in the Distribution Board, as per the Project Documentation. The installation procedures as applicable for MCC and DB shall also in general applicable for motor starter items.
3 Equipment shall be installed level and securely attached to the cubicle frames. The sections shall be joined together with bolts, nuts and washers to form a complete unit assembly. Floor standing equipment shall be installed on concrete plinths as shown on the Drawings.
4.3.1 Earth Bonding
1 Each panel board shall be individually bonded to main earth bar located in the electrical rooms.
2 Each panel section shall be cross bonded to adjacent panel section earthing terminal. END OF PART